Project Summary Cancer cells have metabolic requirements that differ from most normal, non-proliferating cells. To proliferate, cancer cells must transform available nutrients into the varied array of macromolecules that are needed to build a new cell. Each cancer type is unique and will run a metabolic program that depends on the tissue-of- origin, genetic factors, and the local environment. How specific cancers integrate these cancer cell-intrinsic and extrinsic factors to rewire metabolism and support cancer progression is a major unanswered question. My laboratory's long-term goal is to understand how cancer cell metabolism is adapted to support tumor initiation and progression. The metabolic phenotypes of proliferating cells are typically interpreted with an emphasis on either energy generation or the crosstalk between signaling events and cell metabolism. This has led many to focus on how cancer genetics influences metabolic pathway use. We take a different approach that identifies limiting metabolic processes, considers how these are constrained by the extracellular environment, and defines how metabolic limitations are overcome within a physiological tissue context. Our work has provided insight into understanding how glucose metabolism affects cell proliferation. We found that production of nucleotides and oxidized biomass can be metabolic limitations of cell proliferation and tumor growth, and that both cancer cell-intrinsic and environmental factors determine how cells overcome these limitations. We have developed novel tools to study metabolism in various physiological contexts and uncovered metabolic differences between tumors and cancer cells in culture. We have demonstrated how environmental nutrients and cancer lineage can dictate how metabolism is used to support proliferation and determine sensitivity and resistance to drugs used in patients. Our work has charted new research directions for the field and contributed new ideas to exploit altered metabolism to help cancer patients. Using mass spectrometry to trace nutrient fate in cancer models, my laboratory generates hypotheses for how different cancers use metabolism to support cell proliferation and tumor growth. We test these hypotheses using a variety of biochemical and genetic approaches to define how nutrient availability, metabolic pathway regulation, and tissue context constrain how cells use available materials to proliferate. Our current interests include identifying which metabolic processes create bottlenecks for cell proliferation, determining how metabolism is different in different cancers, examining in detail the influence of tissue type, tumor genetics, and tumor microenvironment, and understanding how diet and whole body metabolism influence tumor metabolism and cancer progression. We aim to advance understanding of metabolic pathway biochemistry, its relationship to cancer and mammalian physiology, and identify how best to target metabolism for therapy.